FIG. 1 shows the structure diagram of the waterway system of the coffee maker at the prior art: a water tank 10, a water pump 20, a boiler 30, a check valve 40, a water port 50 and a coffee extractor 60 are arranged in the shell of the coffee maker. The outlet pipe 110 of the water tank 10 is communicated with the inlet of the water pump 20. The water port of the water pump 20 is communicated with the inlet pipe 310 of the boiler 30. The outlet pipe 320 of the boiler 30 is communicated with the inlet of the check valve 40, the outlet of the check valve 40 is communicated to the water port 50 through the outlet pipe 410. The coffee extractor 60 is arranged under the water port 50. The coffee powder is contained in the coffee extractor 60. When the users need to make coffee and the power of the coffee maker is on, the cold water in the water tank 10 is pumped into the boiler 30 by the water pump 20 if the water level in the boiler 30 is lower than the provided water level; when the water level in the boiler 30 is equal to the provided water level, the water pump 20 is shut down, and the heater of the boiler 20 start to heat. When the water temperature in the boiler 30 reaches the provided value, the heater of the boiler 30 stops heating and sends the signal that the water temperature reaches the provided value. And then, if the users press the flush button, the water pump 20 runs again, and the heater of the boiler 30 keeps heating, and then the cold water in the water tank 10 is transmitted to the boiler 30, and then the hot water in the boiler 30 is forcibly pushed into the coffee extractor 60 through the check valve 40 and the water port 50, and then the coffee powder in the coffee extractor 60 is thawed by the hot water, the coffee liquid falls into the coffee cup 70 out of the shell. When the volume of the coffee liquid in the coffee cup 70 reaches the desired volume of the users, the flush button is loosen, is the water pump 20 stops running, and the heater of the boiler 30 stops heating. The hot water in the boiler 30 stops entering the coffee extractor 60 through the check valve 40 and the water port 50, and no coffee liquid falls into the coffee cup 70 out of the shell. The check valve 40 can prevent the hot water in the outlet pipe 410 from back flowing.
Even so, there are a plurality of disadvantages of the coffee maker at the prior art: because the cold water in the water tank 10 is needed to be transmitted in to the boiler 30 by the water pump 20 to get the hot water in the boiler 30 during the coffee cooking process of the coffee extractor 60, the water temperature at the water port 50 is unstable. The dropping of the water temperature at the water port 50 will badly affect the coffee from the coffee extractor 60.